Design and Analysis Three Phase Three Level Diode-Clamped Grid Connected Inverter

In general, Multi-level converter has been utilized widely in many applications, especially in renewable energy aspects. This is because of the associations in high power, medium switch voltage and lower output total harmonics distortion. In this article, the multi-level converter was constructed as a 2 kW output power of the 3 phase 3 level diode clamped grid connected inverter. The proposed multi-level inverter uses a carrier based space vector pulse width modulation scheme in order to produces the desired output voltage. The scheme is the modulation of three identical reference signals, which is 120° phase shifted to each other comparing to a 10 kHz triangular signal. These reference signals comprise of some harmonics in order to generate a space vector PWM signal for switches in the inverter. A Phase Lock Loop (PLL) is utilized together with the controller in order to phase and frequency locking between the voltage at the point of common connection (PCC) and voltage at the grid system. After the proposed inverter connected to the grid system, it can be injected the inverter current into grid system by using the appropriated PI (proportional-integrator) controller within the control scheme. However, L-C low-pass filter is also utilized at the inverter output for reducing harmonic contents. It results to reducing the output harmonic contents. In which, the value of THDv at PCC is less than 5%.